Manual Calibration - Waters GCT Premier Operator's Manual

• Using heptacosa or FC70 the reagent gas can be left at CI+ pressure
and calibrated under CI+ conditions.
5. Tune the system in CI mode with CI gas in.
See also:
6. Set up the nominal mass.
See also:
7. Reduce the pressure of CI gas by turning the CI Flow (%) to 0 or by
clearing the CI Gas check box on the Inlet window.
8. Monitor the whole spectrum from 10 to 290 in tune or acquisition mode.
Result:
tris (trifluoromethyl) triazine in EI+ mode should appear. It may be
necessary to introduce more reference material at this point to produce a
strong enough signal for calibration.
9. Perform an EI calibration applying the metri reference file and the
reference sample tris (trifluoromethyl) triazine.
See also:
Note:
the residual (M+H)+ ion at 286. Use metripci.ref as the reference file as
the C13 isotope has been removed from this file.
10. Once MassLynx accepts a calibration, reintroduce CI gas and adjust the
level of the reference using the reference reservoir pump out valve. Use
the (M+H)+ ion at 286.0027 as the lock mass when using tris
(trifluoromethyl) triazine for CI+ accurate mass experiments.
11. Ensure that the beam is not saturated.
See also:
12. Ensure you count all the ions by setting up the MCP and TDC
Threshold.

Manual calibration

Scanning acquisitions can be calibrated after they have been acquired. This
assumes that the level of error is so small that masses of interest will not fall
outside the mass window of the experiment. Hence, it is usually worth
Tuning the instrument for positive CI on page
Setting up nominal mass on page
The fragment peak at 69 and other fragments characteristic of
TOF calibration of the instrument in EI on page
The C13 isotope of the M+ ion at 286 will be interfered with by
Effects of saturation on peak shape on page
3-25.
B-47.
5-2.
B-51.
Manual calibration 5-19